Question

A man weighing 60 kg runs along the rails with velocity of 18km/hr and jumps into a car of mass 1 quintal standing on the rails. Calculate the velocity with which car will start travelling along the rails

Answer 1

Given

• Mass of the man = 60 kg
• Velocity of the man = 18 km/h
• Mass of the car = 1 quintal

To Find

• Velocity with which the car will start travelling

Solution

● Here we are gonna primarily use the law of conservation of mass, that is, m₁u₁+m₂u₂ = m₁v₁+m₂v₂

✭ Velocity of the car

→ m₁u₁ + m₂u₂ = m₁v₁ + m₂v₂

• m₁ = 60 kg
• m₂ = 1 quintal = 100 kg
• u₁ = 18 km/h
• v₁ = v
• v₂ = v
• v₁ = v₂ as their Velocities are combined

→ 60 × 5 + 100 × 0 = 60 × v + 100 × v

→ 300 = 60v + 100v

→ 300 = 160v

→ 300/160 = v

→ v = 1.875 m/s

∴ The velocity of the car on the rails would be 1.875 m/s

Answer 2

Answer:

Given :-

• Mass of man = 60 kg
• Velocity of man = 18 km/h
• Mass of car = 1 quintal.

To Find :-

Velocity with which car will start travelling along the rails

Here we will use the law of conversion of mass

M1U1 + M2U2 = M1V1 + M2V2

$\sf \implies \: 60 \times 18 + 100 \times 0 = 60 \times v + 100 \times v$

$\sf \implies \: 108 + 0 = 60v + 100v$

$\sf \implies \: 108 = 100v$

$\sf \implies \: v = \dfrac{108}{100}$

$\sf \implies \: v = 1.08 \: mps {}^{2}$